Influence Of Impact Angle Research Articles

Tungsten wall cratering under high-velocity dust impacts: Influence of impact angle and temperature

The integrity of plasma-facing components (PFCs) in fusion reactors is severely tested by high-velocity dust collisions, which occur during explosive events such as runaway electron terminations. These events can expel dust particles at velocities of 0.5 – 1 km/s in current fusion devices and potentially several km/s in advanced reactors like ITER and DEMO, leading to significant material erosion and damage. Given the limitations of existing models, which effectively address only low-velocity impacts, there is a critical need for improved modeling of high-velocity dust-wall interactions. This study utilizes molecular dynamics (MD) simulations to explore the effects of impact angle and target temperature on the interactions between tungsten (W) dust particles and W walls under extreme velocities ranging from 2.5 to 4.5 km/s. Our research focuses on analyzing the morphology of impact craters, and characteristics of ejecta across a range of impact angles (0° to 75°) and with dislocation density for temperatures (300 to 3000 K). Our study reveals that the angle of impact and temperature almost exclusively determine the shape of the crater and the distribution of ejecta, highlighting the critical role of these factors in the dynamics of dust-wall interactions. Comparison with the experimental data obtained from W-on-W impact tests shows a strong correlation with our theoretical predictions.

Simulation of TiN/Ti Multilayer Coating under the Impact of Multiple Particles Based on Cohesive Element

In order to investigate the damage behavior of TiN/Ti multilayer coating under multi-particle impact and the influence of impact angle on erosion resistance, the ABAQUS 2019 software and the cohesive element technology were used for simulation. The results showed that, during the impact process, the upper surface of the TiN layer that was directly below the impact center was mainly subjected to compressive stress, while the lower surface was subjected to tensile stress. At the impact contact edge, tensile stress appeared on the upper surface of the TiN layer, while compressive stress appeared on the lower surface. The increase in the number of impacts leads to an increase in the maximum S11 stress inside the coating and the maximum displacement of the impact center during the impact process. The plastic damage was greater at the locations with higher strain in the Ti sublayer. During the impact process, severe damage occurred in both the top TiN layer and interface areas, and material failure occurred in the impact area. The increase in impact angle leads to an increase in the plastic strain energy of the entire model after the impact and the maximum S11 stress inside the coating during the impact process.

Crown morphology of oblique drop impact on a curved liquid film

The water crown deformation process of a liquid droplet oblique impacting a curved liquid film was simulated by using the coupled level-set and volume-of-fluid method. The morphological differences of the front and back sides of the water crown were compared. The jet sheet is thin and splash occurs at the front, while the crown sheet is stable and smooth at the back. The influence of impact angle on the shape of water crown is analyzed. Influence of impact angle on rear water crown height is quantified. The rim of the water crown presents an inclined line, and the variation of its inclination angle affected by the impact angle is studied. The position deviations of water crown cavities at different impact angles are investigated. With the decrease in impact angle, the spreading coefficient of the front side of the water crown cavity increases, while that of the back side decreases, and the displacement difference of the front water crown is smaller than that of the back water crown.

Mechanical characteristics of composite honeycomb sandwich structures under oblique impact

Carbon fiber reinforced polymer (CFRP) and CFRP-based composite honeycomb sandwich structures are particularly sensitive to impact. The mechanical characteristics of composite honeycomb sandwich structures under oblique impact are studied by numerical simulation and experiment. The oblique impact model is established, and the reliability of the model is verified by the oblique impact test. To further analyze the influence of structural parameters on energy absorption under oblique impact, the influence of impact angle, face sheet thickness and wall thickness of the honeycomb is numerically studied. The results show that the impact angle has an important effect on energy distribution. The structural parameters also have an effect on the peak contact force, contact time, and energy absorption, and the effect is different from normal impact due to the presence of frictional dissipation energy. Compared with normal impact, the debonding of oblique impact will be reduced, but the buckling range of the honeycomb core will be expanded.

Study on the Influence of Sand Erosion Process on the Wear and Damage of Heat-Treated U75V Rail Steel

Abstract Usually, rail materials are exactly affected by the erosion of windblown sand in the desert environment. For this reason, the influence of impact angle, particle velocity, and particle size on the erosion wear behavior of the U75V heat-treated rail steel, a material frequently employed in Chinese railways, were studied in this work. The results showed that, with increasing impact angle, the erosion rate increased between 15 deg and 45 deg, decreased between 45 deg and 75 deg, and then increased again between 75 deg and 90 deg. The highest erosion rate occurred at about 45 deg. When the particle velocity increased, the erosion rate increased approximately in a quadratic way. As the sand particle size increased, the erosion rate presented a decreasing trend. During the initial stage of erosion, shear craters, indentation craters, and ploughing craters were the main surface damage features. The shear craters predominated at the impact angle of 45 deg whereas the indentation craters predominated at 90 deg. During the steady-state of erosion, the rail damage was mainly composed of craters, platelets, and cracks. Both the length and depth of craters increased almost linearly with increasing particle velocity, whereas the increased rate of length was significantly higher than that of depth. The length and depth of craters increased with increasing particle size at 90 deg, whereas only the length increased with increasing particle size at 45 deg. The microstructure evolution and the formation mechanism of platelet at low impact angles were different from those at high impact angles. Platelet formation was the main erosion wear mechanism.

Determination of erosion equation factors of AISI1020 by experimental data

Erosive wear is material removal due to the impingement of granular flow. In the present work, the effects of influencing parameters including flow velocity, incidence angle and grain size on erosive behavior of AISI1020 subjected to a flow of SiC particles has been investigated by employing an erosion wear test machine. The experiments have been performed at the different values of impact angle, flow velocity and particle size. Two tests have been performed for every set of conditions and the average of them has been presented. Results showed that the erosive wear maximizes at the impact angles of 30° and 45°. The flow of small particles resulted in more wear contrast to the large particles. Results also indicated that the influence of flow velocity was higher than the influence of impact angle and particle size. It means that minimizing the flow velocity results in more efficient results to reduce erosion. Moreover, the experimental data were used to determine appropriate coefficients for using in an erosion equation given by literature. New factors gave erosion evaluations which had appropriate accordance with the experimental data.

Influence of Abrasive Materials in Fluidised Bed Machining of AlSi10Mg Parts Made through Selective Laser Melting Technology

Metal Additive Manufacturing technologies development is increasing in a remarkable way due to their great potential concerning the production of complex parts with tailored characteristics in terms of design, material properties, usage and applications. Among all, the most widespread technologies are the Powder Bed Fusion based technologies such as Selective Laser Melting and Electron Beam Melting. However, the high surface roughness of the as-built parts still represents one of the major limitations, making necessary the adoption of post-process finishing to match the technological requirements for most of the fields of application. In this scenario, Fluidised Bed Machining represents an emerging finishing technology that could overcome some of the limitations of the most common methods, especially in terms of feasibility for the treatment of complex parts thanks to the fluid-like mobility of the abrasive material. This work deals with the preliminary tests of the Fluidised Bed Machining of additive manufactured samples using alumina as the abrasive material, investigating the effects of a high abrasive/substrate hardness ratio condition. The experiments were carried out on small plates of AlSi10Mg alloy made through Selective Laser Melting technology, built in the vertical direction with respect to the building plate. The influence of the impact angle and treatment time were investigated under bubbling fluidization conditions. Surface morphology evaluations were carried out pre and post process by means of Confocal Microscopy and Scanning Electron Microscopy (SEM). Weight loss measurements were conducted to evaluate the material removal rates as well. Results show a small influence of the specific impact angle, a slight reduction of the surface roughness and an asymmetrical effect of treatment, acting mostly on the sintered powders forming the peaks of the as-built surface.

An Influence of Factors of Flow Condition, Particle and Material Properties on Slurry Erosion Resistance

Abstract The degradation of materials due to slurry erosion is the serious problem which occurs in the power industries. The paper presents actual knowledge about an influence of individual factors connected with flow conditions, particles and material properties on the slurry erosion resistance. Among the factors connected with operating conditions, an influence of impact angle, and velocity of impact, particle concertation and liquid temperature have been described. In case of the factors connected with solid particle properties, an influence of the size, shape and hardness have been discussed. In the part devoted to the impact of material properties, due to different types of materials, the issues of resistance to erosion of slurries related to the properties of steel, ceramics and polymers are discussed separately. In the paper has been shown that a change of any of mentioned factors causes a change in the erosion rate due to the synergistic effects that accompany to slurry degradation.

Influence of impact angle on size distribution of fragments in hypervelocity impacts

When aluminum alloy 2017-T4 spheres strike thick aluminum alloy 6061-T6 targets at 4 km/s, the size of fragments collected from a test chamber was measured and the effects of impact angle on the size and projected area of the fragments were examined. Impact angle clearly affected the size distribution and projected area distribution of the fragments. The cumulative number of fragments as a function of fragment length and projected area was proportional to the normal component of the impact velocity raised to the power 1.5. When the cumulative number on the vertical axis was divided by the normal component of the impact velocity raised to the power 1.5, experimental formulas with respect to fragment length and projected area were proposed using a bilinear exponential distribution function. The crater shapes on the targets were also examined, as were the area and shape of the indentations created by fragment particles on the witness plate. Their relationship to fragment size distribution was discussed. These results will assist in the revision of ISO 11227 with respect to oblique impact conditions.

A multiple particle impact model for prediction of erosion in carbon-fiber reinforced composites

Material loss and degradation due to erosion remains a major concern in engineering applications for composite materials. A finite element based model has been developed to predict the erosion behavior of unidirectional carbon fiber-epoxy (CFRP) composites subjected to solid particle impacts. In this model, the CFRP plate is subjected to multiple particle impacts at a velocity of 45 m/s, with steel balls as the erodent particles. The Influence of impact angle, erodent particle stream orientation (parallel and transverse to the fiber direction) and erodent particle size has been studied by varying the impact angle from 15⁰–90⁰ and particle sizes considered are of radii 150 µm, 200 µm and 250 µm. The model captures the influence of the erodent particle to particle impacts and the target surface properties by defining two new ratios, kinetic energy ratio, “ηk” and substrate surface property ratio, “ηs”. The cumulative eroded mass predictions are higher for transverse to fiber impact as compared to parallel to fiber impacts. It is also observed that as the erodent size increases the total eroded mass loss increases at all impact angles. The eroded mass predictions obtained from the numerical model compare favorably with the eroded mass results obtained from experimental data reported in the literature.

A pragmatic approach and quantitative assessment of silt erosion characteristics of HVOF and HVAF processed WC-CoCr coatings and 16Cr5Ni steel for hydro turbine applications

In the present study, WC-CoCr hard composite coatings were deposited on the hydro turbine steels using two different thermal spray techniques such as High Velocity Air Fuel (HVAF) and High Velocity Oxy Fuel (HVOF). The slurry erosion tests were performed with three different jet impingement kinetic energies and at five different impact angles. The influence of impact angle on the erosion wear behavior of the coatings was analyzed using CFD simulation technique. Erosion mechanisms were investigated in detail using SEM and laser scanning confocal microscopy. Among all the WC–CoCr coated samples, the HVAF coating sprayed at highest spray velocity has shown superior erosion resistance compared to the HVOF coatings. It could be attributed to the better adhesion, higher density, enhanced hardness and surface compressive residual stresses coupled with lower oxidation of the coated samples. The erosion wear mechanisms were found to be nearly micro-cutting and plowing with layered material removal at a lower impact angle and a low cycle fatigue linked to repeated impact leading to rounding of the edges and brittle cracking of the WC grains at normal impact conditions.

Wpływ kąta zderzenia oraz wilgotności na wirtualne testy zderzeniowe TB11 bariery SP-05/2

W pracy przedstawiono badania numeryczne wpływu wybranych czynników, tj. kąta zderzenia oraz suchej/mokrej nawierzchni drogi i pobocza, na przebieg wirtualnego testu zderzeniowego TB11. Testy dotyczą bariery klasy N2-W4-A w łuku poziomym wklęsłym o promieniu 150 m, uderzanej samochodem Geo Metro pod kątem 20°. Nakładka jest łatwa w montażu, bez ingerencji w barierę stalową, poprzez mocowanie za pomocą łączników śrubowych z prostokątnymi podkładkami gumowymi, w wolnych otworach prowadnicy. Obliczenia numeryczne przeprowadzono w środowisku LS-Dyna, wykorzystując model pojazdu Geo Metro zaczerpnięty ze strony NCAC i odpowiednio zmodyfikowany. Analizą objęto parametry jakościowe i ilościowe określające testy zderzeniowe, zgodnie z normami PN-EN 1317-1:2010 i PN-EN 1317-2:2010. Zaprojektowana nakładka kompozytowo-pianowa zapewnia przyjęcie wirtualnych testów zderzeniowych dla normowego kąta zderzenia, w warunkach suchych i mokrych. Wpływ kąta zderzenia na przebieg testu zderzeniowego jest złożony. Zwiększenie kąta do 30° może prowadzić do niespełnienia warunku wyprowadzenia pojazdu na jezdnię.

Solid Particle Erosion of Selected HVOF Sprayed Coatings

The paper involves the subject and the chosen results of up to now solving of work package “Development of advanced surface treatment of components used in parts of turbines working under the condition of operational temperatures of steam using the HP/HVOF technology of thermal spraying” of the Competence Centre project “Centre of Research and Experimental Development of Reliable Energy Production”. The subject belongs to the field of material engineering and results of solving contribute to fulfilling the main project aim, which is a long time safeguarding of safe, reliable and financially available both classical thermal and nuclear sources of electric power, which consists in extending service life of existing and building new turbo generator blocks. The erosion wear resistance is one of the areas, which were observed. The impact of hard particles on the surface under variable impact angles was simulated in laboratory conditions using an in-house equipment. The wear resistance of selected HVOF sprayed hardmetal and super-alloy coatings was measured and the wear mechanism was evaluated. A strong influence of impact angle on both material volume loss and wear mechanism was monitored. The superior erosion wear properties of super-alloy coatings were proved, regardless the higher hardness of hardmetal coatings.

Effect of nose shape on semi-armor-piercing warhead penetration performance

The numerical simulations of different head shape semi-armor-piercing warheads penetrating thin steel target are done using the finite element software ANSYS/LS-DYNA, and the whole process of different nose shape semi-armor-piercing warheads vertically penetrating the thin steel plate is compared. Besides, the influence of impact angle on penetration performance of three different nose shape projectiles is researched. The analysis results indicate that the nose shape has a significant influence on semi-armor-piercing warhead penetration performance. The effect of impact angle on the three kinds of projectiles’ residual kinetic energy and deflection is different. The research results provide references for designing of warhead and battlefield damage assessment.

The effect of impact obliquity on shock heating in planetesimal collisions

AbstractCollisions between planetesimals in the early solar system were a common and fundamental process. Most collisions occurred at an oblique incidence angle, yet the influence of impact angle on heating in collisions is not fully understood. We have conducted a series of shock physics simulations to quantify oblique heating processes, and find that both impact angle and target curvature are important in quantifying the amount of heating in a collision. We find an expression to estimate the heating in an oblique collision compared to that in a vertical incidence collision. We have used this expression to quantify heating in the Rhealsilvia‐forming impact on Vesta, and find that there is slightly more heating in a 45° impact than in a vertical impact. Finally, we apply these results to Monte Carlo simulations of collisional processes in the early solar system, and determine the overall effect of impact obliquity from the range of impacts that occurred on a meteorite parent body. For those bodies that survived 100 Myr without disruption, it is not necessary to account for the natural variation in impact angle, as the amount of heating was well approximated by a fixed impact angle of 45°. However, for disruptive impacts, this natural variation in impact angle should be accounted for, as around a quarter of bodies were globally heated by at least 100 K in a variable‐angle model, an order of magnitude higher than under an assumption of a fixed angle of 45°.

Research on the Impact between Balls and Re-Circulating Mechanism of Ball Screws

A Mechanical model of impact and contact between the ball and re-circulating mechanism in ball screw was brought forward according to the Hertz contact model and classical impact theory, along with the joint relationship of re-circulating mechanism and nut taken into account. Then the formula of the impact force and contact time was induced, which the elastic coefficient of restitution was considering in contact time calculation. Moreover, a special test unit was designed for contact time measurement and the contact time was measured. The result indicates that the new model proposed in this paper is closer to the practical situation than the old model proposed in literature. Based on works mentioned above, the influence of impact angle, parameters of structure and material on impact force was analyzed by numerical simulation.

Erosive Wear Behaviour of WC Filled Glass Epoxy Composites

The effect of incorporation of tungsten carbide (WC) powders on erosive wear behaviour in glass fabric-epoxy (G-E) composites was investigated and findings were analyzed. The vacuum-assisted resin infusion (VARI) technique was employed to fabricate the composite specimens. The effect of different impact velocities (40 and 80 m/s) and impact angles (300 to 900) on the performance of the wear resistance of the composites were measured. The results of erosive wear losses, impact angle, and impact velocity and erosion rate of filled and unfilled glass-epoxy composites were analyzed and discussed. The influence of impact angle on erosive wear of all composites shows brittle behaviour with a maximum erosion rate at 900 impact angle. The WC filled G-E composite exhibited a lower erosion rate as compared to that of unfilled G-E composites. The worn surface features of unfilled and filled G-E composites were examined using scanning electron microscopy (SEM) and results indicates more severe damage to matrix and glass fiber in unfilled composite system as compared to WC filled composites.

Influence of impact angle on the interaction between Co55 nanocluster and Cu (0 0 1) substrate: Ionized cluster beam deposition

Using a classical molecular dynamics method, the influence of impact angle was studied on the ionized cluster beam (ICB) deposition. A many-body tight binding potential was employed to simulate the interactions among the atoms, in which the Co55 (55atoms/cluster) nanocluster with the total energy of 110eV was deposited on a Cu (001) substrate, whose temperature was set at 300k. The quantitative of kinetic energy of the cluster, maximum temperature substrate, cluster center of mass and diffusion area of the cluster were proposed to evaluate the interacting mechanism nanocluster and substrate. Also, the influence of impact angle was investigated on the Co–Co and Cu–Co radial distribution function and the adhesion between cluster and substrate. The simulation data demonstrated the decrease of the maximum temperature substrate with the increase of impact angle. The results indicated the decrease in the maximum depth penetration with the increase in the impact angle. The thin film formed by Co55 nanocluster with the impact angle of 30° had the minimum adhesion with the substrate.

Nonlinear Damage and Failure Behavior of Brittle Rock Subjected to Impact Loading

Abstract The damage and fragmentation of rock induced by impact loading is one of typical nonlinear problems in underground engineering. Rock specimen such as rock plate was found to become invalid under impact loading. This paper presents brittle fragmentation for dynamic damage of rock plate based on the edge-on impact (EOI) test with varying impact velocities (10 m s -1 to 40 m s -1) and impact angles. High-speed camera was used to study the relation among crack initiation and propagation, impact velocity and impact angle. The patterns of fracture of the crack under impact are observed and the influence of impact angle on the growth of the crack is analyzed. The results demonstrate that only when the impact velocity is less than a critical value does a damaged zone, whose size increases with the impact velocity, appear on the edge of the sample. When the velocity exceeds the critical value, some radial cracks occur around the damaged zone and extend outward from the boundaries of damaged zone. The radial crack length and damaged zone increase with impact velocity and are influenced by the impact angle. However, at a certain velocity, the damage zone decreases and the crack length increase. It shows that there was an obvious incubation period of crack forming. According to test results, the study found that the impact velocity of this jump is about 25 m s -1 –3 m s -1 and scope of the impact resistance optimized angle is about 15 ° –30 ° .

Nonlinear Damage and Failure Behavior of Brittle Rock Subjected to Impact Loading

Abstract The damage and fragmentation of rock induced by impact loading is one of typical nonlinear problems in underground engineering. Rock specimen such as rock plate was found to become invalid under impact loading. This paper presents brittle fragmentation for dynamic damage of rock plate based on the edge-on impact (EOI) test with varying impact velocities (10 m s -1 to 40 m s -1) and impact angles. High-speed camera was used to study the relation among crack initiation and propagation, impact velocity and impact angle. The patterns of fracture of the crack under impact are observed and the influence of impact angle on the growth of the crack is analyzed. The results demonstrate that only when the impact velocity is less than a critical value does a damaged zone, whose size increases with the impact velocity, appear on the edge of the sample. When the velocity exceeds the critical value, some radial cracks occur around the damaged zone and extend outward from the boundaries of damaged zone. The radial crack length and damaged zone increase with impact velocity and are influenced by the impact angle. However, at a certain velocity, the damage zone decreases and the crack length increase. It shows that there was an obvious incubation period of crack forming. According to test results, the study found that the impact velocity of this jump is about 25 m s -1 –3 m s -1 and scope of the impact resistance optimized angle is about 15 ° –30 ° .